1. Field of the Invention
This invention is directed to the field of medical devices and testing and, more particularly, to apparatus and techniques for evaluating urinary stress incontinence.
2. Description of the Prior Art
According to the American Academy of Family Physicians, urinary incontinence (UI) affects approximately twelve million persons in the United States alone. Although urinary incontinence can occur in both men and women, it is most common in women over the age of 50. There are many causes of UI, including age related atrophic changes in the genitourinary anatomy in women after menopause, enlargement of the prostate in men as well as generalized weakening of the pelvic floor muscles, medication side effects, immobility, infection of the urinary tract and various underlying medical co-morbidities including diabetes and hypercalcemia.
There are four basic types of urinary incontinence; functional, overflow, urge and stress. Stress incontinence occurs when there is a sudden pressure on the lower abdominal musculature, such as with a cough, sneeze, laugh or lifting. Stress incontinence is often secondary in part to weakening of the pelvic floor musculature, and is common after childbirth or abdominal surgery. It has been estimated that stress urinary incontinence occurs at least weekly in one third of adult women. (1) Additional reports indicate that more than 65% of female incontinence patients in the United States or 8.3 million women experience stress urinary incontinence. Of these women, approximately 85% or 7 million have incontinence primarily due to hypermobility of the bladder outlet, and approximately 15% or 1.3 million have incontinence primarily due to an intrinsic sphincter deficiency. Regardless of the etiology of UI, for the affected person it maybe a source of significant embarrassment and social isolation. As a result of this social stigma, many patients are reluctant to address this issue with their physician. Most primary care physicians “screen” for urinary incontinence by verbal or written questioning of the patient only. Additional basic evaluation may include a voluntary cough stress test, voiding diary, post void residual urinary volume, and urinalysis. (2)
A patient experiencing urinary incontinence must be properly diagnosed to identify the specific type of incontinence from which the patient suffers. The treatments may be different, depending on the type of incontinence. Therefore, proper diagnosis becomes important at least for that reason.
Stress incontinence may result primarily in older women due to loss of extrinsic support for the pelvic organs and for the neck of the bladder. The tissues of the pelvis and of the distal urethra contain estrogen and progesterone receptors. Following menopause—and decrease of the hormones, the tissues of the urethra may lose resiliency and become somewhat flaccid. Under those conditions, any increase in intra-abdominal pressure causes urine in the bladder to be pushed outwardly as resistance in the urethra is overcome, resulting in leakage of urine. This condition is known as stress incontinence and occurs in the absence of contractions by the detrusor muscle of the bladder. Stress incontinence may be responsive to treatment with exogenous estrogens, although this is not an effective treatment for all patients, particularly depending on age. Alternative treatments may include pelvic muscle exercises, α-adrenergic agents, such as phenylpropanolamine, that act on the a-adrenergic receptors along the urethra and increase urethral tone.
The most common cause of urinary incontinence, however, is detrusor hyperreflexia, or hyperactivity of the detrusor muscle. This type of incontinence is believed to result from lack of inhibition of the detrusor muscle due to a decreased detrusor reflex in the brain stem. Nevertheless, in most affected elderly there appears to be no underlying neurological defect. In this condition, treatment may include antispasmodic agents which tend to relax the wall of the bladder.
A typical test employed to distinguish these two types of urinary incontinence is one which increases intra-abdominal pressure so as to, in turn, put pressure on the bladder. The Valsalva maneuver is one such test. In this technique, the patient generates a muscular contraction of the chest, abdomen and diaphragm in a forced expiration against a closed glottis. This increases pressure within the thoracic cavity and also in the abdominal cavity. The Valsalva maneuver also refers to raising the pressure in the nasopharynx by a forced expiration with the mouth closed and the nostrils pinched, for example, to clear the patency of the Eustachian tubes. Other testing techniques involve having the patient jump up and down to jostle the bladder, or bend down so as to compress the abdomen. Yet another method involves having the patient generate one or more strong voluntary coughs.
It is known, however, that some patients are unable to perform these physical acts. For example, a patient may not be able to jump, or to bend, or to generate a strong voluntary cough. Additionally, there are some patients who will not be correctly diagnosed on the basis of the cough test, perhaps because their coughs are insufficiently strong. Accordingly, there is a need for alternative or supplementary tests that will aid in diagnosing urinary stress incontinence.
A rather complete discussion of methods of evaluating urinary incontinence is found in a February 2006 article by JL Martin et al. entitled “Systematic review and evaluation of methods of assessing urinary incontinence (hereinafter referred to as Systematic review).”
Problems of the Prior Art
One of the problems associated with the prior art techniques is that some patient's are unable or are unwilling to perform the physical acts to the extent needed. For example, a patient may not be able to jump, or to bend, or to generate a strong voluntary cough. For some patient's they maybe able to perform these acts, but be unwilling to do so because an involuntary release of urine maybe embarrassing or contrary to what is considered proper in society.